Together with improvement in speed and increase in capacity of signal transmission between central processing units (CPUs) in a high-end server, a supercomputer or the like, breaking down of the limit to electric signal transmission is demanded.
Related arts are disclosed in Japanese Laid-open Patent Publication No. 2007-194967, Japanese Laid-open Patent Publication No. 62-7227 or Japanese Laid-open Patent Publication No. 08-237314.